1. An Evaluation of Phase IV exercise Participants
School of Sport and Exercise Sciences, University of Kent, The Medway Building, Chatham Maritime, Kent. ME4 4AG
S. Meadows, A. Cunliffe, C. Prior, K. Small & A. Ferrusola-Pastrana
Correspondence:
Introduction
Exercise training is considered a cornerstone intervention in Phase III & Phase IV cardiac rehabilitation (CR). The typical presentation of CR exercise training is a circuit format, alternating cardiovascular (CV) and muscular–strength endurance (MSE) stations. However, the benefits of exercise are only retained with adherence. Very little evaluative work has been conducted on those who remain involved in Phase IV to investigate their health & functional status in relation to key cardiovascular disease (CVD) risk management criteria, i.e. BMI, waist circumference, blood pressure & fitness.
Table 1. Health & functional data for Phase III and Phase IV cohorts
Assessment
Phase III Mean (±SD)
n = 465
Phase IV Mean (±SD)
n = 34
Diff
Demographic (years)
Age
69.00 (±6.11)
72.74 (±5.70)
3.74
Female Age (n=10)
69.63 (±5.88)
71.30 (±5.10)
1.67
Male Age (n=24)
68.83 (±6.17)
73.33 (±5.94)
4.50
BMI (kg.m2)
BMI na
27.31 (±3.54)
Female BMI
26.88 (±2.79)
Male BMI
27.48 (±3.85)
Waist Circumference (cm)
Female Waist Circumference
87.25 (±8.27)
Male Waist Circumference
99.72 (±11.92)
Blood Pressure (mmHg)
SBP
(±16.25)
(±16.33)
9.66
DBP
70.92 (±9.17)
76.85 (±9.48)
5.93
Functional (Fitness) Status
6MWD (m)
(±86.44)
(±88.92)*
69.22
Female 6MWD (m)
(±85.27)
(±55.94)
55.71
Male 6MWD (m)
(85.06)
(±94.9)*
79.25
Walk Speed (m/s)
1.16 (±0.24)
1.36 (±0.25)
0.20
Female Walk Speed (m/s)
1.08 (±0.24)
1.24 (±0.16)
0.16
Male Walk Speed (m/s)
1.19 (±0.24)
1.41 (±0.26)
0.22
Metabolic Equivalents (METs)
METs in 6MWD
3.00 (±0.41)
3.33 (±0.42)
0.33
Female METs in 6MWD
2.85 (±0.41)
3.12 (±0.27)
0.27
Male METs in 6MWD
3.03 (±0.41)
3.38 (±0.45)
0.35
Study Aims
To evaluate the health & fitness of long-term Phase IV cardiac rehabilitation (CR) participants.
Methods
Recruitment
Phase III dataset was obtained from the local CR team. Total n = 465; males n = 366 (78.71%); females n = 99 (21.29%). Mean age 69 (±6.11) years.
Phase IV participants n= 34 recruited from a local Phase IV session; males n = 24 (70.59%); females n = 10 (29.41%). Mean age (±5.71) years with at least 6 months engagement in a once weekly CR circuit exercise class.
Tests
Completed anthropometric (BMI & waist circumference), health measurement (resting blood pressure), and 6-minute shuttle walking distance (6MWD) for functional capacity (fitness).
Key: na = data not available *p<0.001
Discussion
Encouraging to see this Phase IV group have a higher functional capacity (6MWD & METs) compared to Phase III counterparts. However, concerns should be raised about absolute levels of fitness (3 – 4 MET range for a 6-minute physical effort), overweight BMI accompanied by excessive waist circumference measurements in 80% of the female cohort and 41% of the males. Normotensive SBP & DBP, but higher in Phase IV could reflect a future risk of hypertension.
Phase IV CR Exercise Intervention (1 x week)
Warm Up (15 minutes)
Graded CV warm-up, consisting of various multi-directional mobility movements, co-ordination & dynamic stretching exercises.
Cardiovascular (CV) Conditioning Component (40 minutes)
Circuit format of alternating CV & MSE exercises (using resistance bands or light hand weights), e.g. shuttle walking, standing press-ups, sit to stand, step-ups, chest press, etc. The circuit was continuous & lasted for 40 minutes, consisting of 1 minute exercise stations (40 exercise stations). Exercise intensity monitored through a combination of pulse monitoring and RPE (midpoint & end of circuit). Participants encouraged to exercise at an RPE of dependent on ability.
CV Cool Down & Stretching (10 minutes + 10 minutes)
Easy 10 minute walking cool down with stationary activities for those less mobile, followed by functional mobility & static stretching exercises to promote muscle lengthening & avoid adaptive shortening, especially around the chest & shoulders. Static & dynamic balance exercise challenges also incorporated.
Conclusion
A small improvement in sub-maximal functional capacity achieved in this Phase IV CR population, as measured by 6MWD. However, the MET equivalent value for this effort was only in the moderate intensity range and below the 5-MET threshold normally associated with higher risk stratification. There is scope for education reinforcement related to healthy weight management to control for the risk associated with overweight / obesity, as measured by BMI and waist circumference in both the male and female Phase IV CR population.
Limitations
Due to resource limitations & data anonymization it was not possible to identify individual Phase IV patients in Phase III data; only group comparisons were completed. 6MWD test did not provide a peak value, although participants were instructed to walk as far as possible in 6-minutes, therefore MET capacity is likely to be under-estimated.
Further Research Recommendations
Supervised CR exercise can help CVD patients regain & sustain their health, independence & quality of life. It also provides an effective secondary prevention strategy, helping to reduce future costs & burden to carers & the healthcare system. Continued engagement with Phase IV exercise provides an opportunity for further improvement in health & functional status as part of CVD risk management. This work provides a compelling case for longitudinal studies tracking CVD patients to ensure behaviours & education messages promoted early in the CR journey are continued, reinforced & patients receive follow-up evaluation on key metrics for CVD reduction.
Results (mean ±SD)
BMI
Individual BMIs were not available for Phase III cohort; only reported if BMI > 25 kg.m2 but there was a 10% increase in those with a BMI > 25 kg.m2 from the Phase III to Phase IV group (66% & 76% respectively). The mean BMI in the Phase IV cohort was (±3.57) kg.m2 (= overweight category).
Waist Circumference
Data not available for Phase III. Regional weight distribution was measured by waist circumference in Phase IV cohort (±8.27) cm in females (healthy = 80cm) & (±11.92) cm in males (healthy = 94 cm).
Resting Blood Pressure
Blood pressure remained in a normotensive range, although a small increase was noted in SBP & DBP in Phase IV group.
Functional Capacity (Fitness) Status (6MWD)
6MWD improved from a mean of (±86.44) m in Phase III to (±88.92) m, which reflected a 14.18% improvement. Using the ACSM (2014) formula based on walking speed (m.min-1) in the 6MWD test, this represented a MET improvement from 3 to 3.33 METs from Phase III to Phase IV for a sub-maximal walking effort.
Key References
Anderson, L. et al. (2016) Exercise-based cardiac rehabilitation for coronary heart disease: Cochrane systematic review & meta-analysis. Journal of American College of Cardiology, 67(1), 1-12.
Franklin, B.A. et al. (2018) Using metabolic equivalents in clinical practice. American Journal of Cardiology, 121,
Feuerstadt, P. et al. (2007) Sub-maximal effort & tolerance as a predictor of all-cause mortality in patients undergoing cardiac rehabilitation. Clinical Cardiology, 30,